Angel Island
We started development on "3" with a story in mind, but it turned out we couldn't make it in time without problems. In the end, the game ended up being cut in half (laugh). This stage starts off with a certain impact, as the flame thrower machines set fire to the island and change the color considerably. (Sonic Team, Izuka)

Hydrocity
Thinking we would make a high-speed stage similar the previous games, we based this stage on Chemical Plant. The map size was already at the limit of the MegaDrive's RAM with Sonic 2, but thanks to the efforts of our programmers we were able to make them even bigger. There are also routes made specifically for each character. (Izuka)

Marble Garden
Even though we used this pattern once before, we wanted to do another stage where the ground shakes GAGAGA ever since Sonic 1. In the first Zone, where Eggman is digging for jewels, we wanted that machine to appear and chase after Sonic from behind, something like that, but we didn't get to it this time. (Naka) (1)

Carnival Night
While developing in America, we would see these portable carnival rides come in around shopping centers, and that was the idea we went with for this stage. When you think of carnivals of course there are ferris wheels and teacup rides, but it seems like generally there were a lot of things that just pushed and spun you around really fast (laugh), my main memory was that they were ususually scary! (Naka)

Ice Cap
While developing, we went snowboarding a lot at a nearby resort. People kept getting injured though… (laugh) Originally this stage was planned to begin after zone 8 (Flying Battery). Sonic was going to break down the door from the airship and make a snowboard out of it on the way down. The other characters can fly, so they wouldn't appear in that event. (Naka)

Launch Base
This is the place where you can see the construction site where Eggman is rebuilding the Death Egg, hidden among the various ruins on the island. You never really see the Death Egg in Sonic 2, but here you can see it quite clearly. This is the climax at the midpoint of the story. (Izuka)

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Translator's notes:
(1) He mentions the first zone specifically, even though Eggman doesn't appear until zone 2. He might be refering to the midboss.